. A text book of physics, for the use of students of science and engineering . ss-wire, and read thevernier. Remove the prism and take the direct reading with the tele-scope facing the collimator. The difference between these two readingsis the angle of minimum deviation. Knowing the angle of the prism fromthe previous experiment, calculate //, from equation (4) (p. 624). _sin|(A+D) sin ^A Expt. 144.—Determination of the refractive index of a liquid. Place theliquid in a bottle having two plane faces inclined to each other. Findthe angle between the plane faces by the method of Expt. 142. Find
. A text book of physics, for the use of students of science and engineering . ss-wire, and read thevernier. Remove the prism and take the direct reading with the tele-scope facing the collimator. The difference between these two readingsis the angle of minimum deviation. Knowing the angle of the prism fromthe previous experiment, calculate //, from equation (4) (p. 624). _sin|(A+D) sin ^A Expt. 144.—Determination of the refractive index of a liquid. Place theliquid in a bottle having two plane faces inclined to each other. Findthe angle between the plane faces by the method of Expt. 142. Find theminimum deviation by the method of Expt. 143, and calculate /x. Empty 628 LIGHT CHAI\ the bottle and make sure that the faces themselves do not produce anydeviation. Dispersion.—On allowing a narrow beam of light to fall on a prism,the emergent beam will not be deviated merely, but will, in general,exhibit a variety of colours. The screen B (Fig. 583) placed in a beam of sunlight or in front of anelectric arc, allows a narrow beam of white light to fall upon the - W. Fig. 583.—Dispersion produced by a prism. prism A. On placing the white screen C to receive the emergentbeam, it will be seen that this is spread out as well as deviated, givinga band of colour, red at R, passing through yellow, green, and blueto violet at V. This band of colour is called a spectrum, and thephenomenon of the splitting up of light in this manner is calleddispersion. If by any means the differently coloured beams, into which theoriginal white beam is decomposed, be recombined, they again forma white beam. Thus, if a second prism A with its vertex to the baseof A (Fi<j. 583) be placed to receive the emergent beams, a white spotis produced at W, because of the recombination of the differentlycoloured beams into a white beam. This result makes it appearthat the original white light consists of a mixture of an infinitenumber of differently coloured portions, and that these have differentrefr
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Keywords: ., bookcentury1900, bookdecade1910, bookpublishe, booksubjectphysics
